Hepatitis C is the most common form of chronic liver disease in the U.S. with an estimated 4-5 million people infected. The disease is characterized by hepatic inflammation and progressive fibrosis leading to eventual development of cirrhosis and/or hepatocellular carcinoma in as many as 20-30% of individuals. Alcohol consumption greatly increases the severity and rapidity of disease progression but the mechanism of alcohol/HCV synergy is unknown. Development of new therapeutic approaches has been hampered by the limited experimental models systems available and a lack of understanding of the pathogenic mechanisms involved. The long-term objective of this study is to characterize a transgenic mouse model which expresses HCV proteins in the liver and to use this model to determine the role of oxidative stress and mitochondrial dysfunction in producing the increased liver toxicity of alcohol in chronic hepatitis C. The specific aims are 1. To examine the mechanisms and consequences of HCV protein-induced stimulation of ROS production. These experiments will use cell culture expression systems to determine the effects of HCV core protein on basal and TNF-induced ROS production and examine the source of abnormal ROS. The consequences of core-induced ROS changes to cell survival and its modification by antioxidants and NF-XB activation will be determined. Changes in gene expression induced by HCV protein expression in cell lines will be measured using RNase protection assays. 2. To determine the effects of HCV protein expression on ethanol-induced liver injury. Chronic alcohol feeding of normal and a-ansgenic mice will be performed and liver histology and oxidant injury compared. Alcohol induced changes in liver gene expression will be measured using DNA microarrays. 3. To evaluate antioxidant based approaches to modify HCV/alcohol-induced cell and liver injury. Ethanol-fed transgenic animals and cell culture systems will be used to determine the potential to modify HCV/alcohol -induced liver injury with antioxidants and anti-TNF antibodies. Successful completion of these studies will result in the development of a new model for the study of HCV-induced liver injury, new insight into the role of oxidative stress in HCV/alcohol induced liver injury, and a preliminary evaluation of potential therapeutic modalities for this disease.